My future mother-in-law is totally crazy, and I need advice badly! Background: She has two daughters and one son (my fiance). Her oldest daughter has completely cut her out of her life. Since they last spoke, this daughter has moved to the opposite side of the country, gotten married, and has now had her first child. She refuses to speak to her because of their past, and her new family has never met her. The second daughter lives closer and is in contact, but the grandkids call her their "mean grandma" and she is not allowed to babysit them. My fiance and this sister seriously think that she is mentally unstable, but cannot convince her to seek help. She is incredibly needy, and I believe jealous of me for taking away her son (she's never been married and is all alone now). On the few occasions I have seen her, she has found a way to draw everyone’s attention to her. When she thinks she’s being ignored, she sulks, says that she’s going to commit suicide, and calls me names in front of him. She has totally flipped out at me for getting involved in his business, although I think the fact that we’re getting married warrants my involvement. She even tells him that she wants me nowhere near her (then complains that I’m ignoring her, go figure). My fiance has tried to talk to her, but he says she has been this way his whole life; him talking to her certainly makes no difference that I can see. She needs treatment and probably medication, but since she doesn’t think there’s anything wrong, there’s really no way to force it on her. Back to my point: I am absolutely terrified of her ruining our wedding (she still thinks I manipulated her son into buying me a ring). I wouldn’t doubt for a second that she could and would do it. Personally, I’d love to do what the first sister did and not invite her at all. Unfortunately for me, my fiancé can’t bring himself to do that. So I’m trying to figure out my options. I’ve seriously contemplated eloping, just so that she can’t be there. But I would have a very hard time without MY parents, who I am very close to. Please, any advice so that I can relax on my big day without the fear that she’ll cause a scene and make it all about her? How do I remain in control when I know that talking to her nicely doesn’t do a bit of good?